2.1 Earth's Crust in Motion

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Vocabulary

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earthquake: when the earth shakes beneath the crust.
stress: to change the shape on a rock.
shearing: cause rock to slip past each other.
tension: this causes to stretch rocks.
compression: pushes the rock toward each other.
deformation: is any change that happens to earth's crust.
fault: is a break in the Earth's crust where groups of rock slide past each other.
strike-slip fault: is a fault where rocks from different sides that move past each other in a up and down motion.
normal fault: is a fault which has a hanging wall that slides downward, this is caused by tension in the crust.
hanging wall: is a block of rock that forms on the upper part of a fault.
foot wall: is the block of rock which forms the lower part of a fault.
reverse fault: is a fault that has a hanging wall that slides upward.
fault-block mountain: a mountain that is being created where a normal fault uplifts a block of a rock.
folds: a bend in a rock that forms where the part of the Earth is compressed.
anticline: an upward fold in a rock that is formed of the Earth's crust by compression.
syncline: a downward fold in a rock that is formed in the Earth's crust by compression.
plateau: is a land form that has more less leveled surface and that is elevated high above the level of th sea

Outline

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Stress in the Crust

• the movement in earthquakes result to forces that are called stresses
  • stress is a kind of force which changes the shape or volume of an object

Types of Stress

• there are three different kinds of stress, the shearing, the tension, the compression, and the deformation stresses
  • each stress has a unique force of bending, stretching, breaking, tilting, folding, and sliding the Earth's crust

Kinds of faults

• faults are breaks in the Earth's crust where a group of rocks slip past each other
  • fault usually appear where plate boundaries are,and where plate motions occurs
    • there are usually three types of faults, the strike-slip fault, the normal fault and the reverse fault
• shearing is the stress that creates the strike-slip fault
  • by forming the boundary between two plates is also known as the transform boundary
• tension forces create normal faults in the Earth's crust
  • normal faults go in an angle so on side goes up and one go down in a slanted direction
    • the half that goes upward is called the hanging wall and the half that goes downward is called the footwall
• the compression force creates the reverse fault
  • the reverse fault is the same as the reverse fault, but the movement is in the opposite directions

Friction along faults

• friction, a force that opposes the motion of one surface to another surface
  • depending on the fault there will be a certain amount of friction between the opposite side of faults

Mountain Building

• the force of plate movements can build up the surface of the Earth
  • movements of faults can change a flat plain to a bumpy mountain
• when a block of rock is uplifted by a normal fault it forms a fault block mountain
  • where two plates moved away from each other, the tension forces produce a lot of normal faults
    • hanging fault fault from each slips down
• bends in rocks are called folds when the compression shortens part of the crust of the Earth
  • collisions of two plates can cause compression with two plates
• fold that goes upward in an arch is called anticline and the opposite is called sycline
  • both anticline and sycline happen where compression takes place on the Earth's surface
• forces that could raise mountains are the forces that raise plateaus
  • plateaus are a large area of flat plain land that has an elevation above sea level